A public bug bounty program is one that is open to anyone who wants to participate. This program may prohibit some researchers from participating based on the researcher's level and track record, but in general, anyone can participate in a public bounty program and this includes the scope, the rules of engagement, as well as the bounty guidelines. A public program is accessible by all researchers on the platform, and all bug bounty programs outside of the platforms are also considered bug bounty programs.

A private bug bounty program is one that is an invite-only program for selected researchers. This is a program that allows only a few researchers to participate and the researchers are invited based on their skill level and statistics. Private programs only select those researchers who are skilled in testing the kinds of applications that they have. The programs tend to go public after a certain amount of time but some of them may never go public at all. These programs provide access only to those researchers that have a strong track record of reporting good vulnerabilities, so to be invited to good programs, it is required to have a strong and positive record.

There are a few differences between a public and private program. Conventionally, programs tend to start as private and over time evolve into the public. This is not always true but, mostly, businesses start a private bug bounty program and invite a group of researchers that test their apps before the program goes public to the community. Companies usually consider a few factors before they start a public program. There has to be a defined testing timeline and it is advised that companies initially work with researchers who specialize in that particular area to identify the flaws and vulnerabilities.

Most of the time, the companies do not open their programs to the public and limit the scope of testing as well so as to allow researchers to test these applications specifically in the sections that are critical. This reduces the number of low-severity vulnerabilities in out-of-scope applications. Many organizations use this technique to verify their security posture. Many researchers hunt for bugs in applications mainly for financial gain, so it is crucial that the organization outlines their payout structure within the program's scope. There are a few questions before anyone would want to start to participate in a bug bounty program; the most important one is What is the end goal of the program going public versus keeping it private?